Boron containing heterocyclic compound for OLEDs, an organic light-emitting device, and a formulation comprising the boron-containing heterocyclic compound

ABSTRACT

A boron containing heterocyclic compound for OLEDs is disclosed, which exhibits narrow line shape and high photoluminescence quantum yield. The compound has a new structure of boron-containing heterocyclic ring. The compound can be used in OLEDs as emitters, hosts, charge blocking materials, charge transport materials, etc. The compound can be easily used in the manufacture of OLEDs, which can provide efficient OLEDs and long lifetime. In addition, an organic light-emitting device comprising the compound and a formulation are also disclosed.

This application claims the benefit of U.S. Provisional Application No.62/548,413, filed Aug. 22, 2017, the entire content of which isincorporated herein by reference.

1. FIELD OF THE INVENTION

The present invention relates to compounds for organic electronicdevices, such as organic light emitting devices. More specifically, thepresent invention relates to a boron containing heterocyclic compoundand a compound formulation comprising the boron-containing heterocycliccompound.

2. BACKGROUND ART

An organic electronic device is preferably selected from the groupconsisting of organic light-emitting diodes (OLEDs), organicfield-effect transistors (O-FETs), organic light-emitting transistors(OLETs), organic photovoltaic devices (OPVs), dye-sensitized solar cells(DSSCs), organic optical detectors, organic photoreceptors, organicfield-quench devices (OFQDs), light-emitting electrochemical cells(LECs), organic laser diodes and organic plasmon emitting devices.

In 1987, Tang and Van Slyke of Eastman Kodak reported a bilayer organicelectroluminescent device, which comprises an arylamine holetransporting layer and a tris-8-hydroxyquinolato-aluminum layer as theelectron and emitting layer (Applied Physics Letters, 1987, 51 (12):913-915). Once a bias is applied to the device, green light was emittedfrom the device. This invention laid the foundation for the developmentof modern organic light-emitting diodes (OLEDs). State-of-the-art OLEDsmay comprise multiple layers such as charge injection and transportinglayers, charge and exciton blocking layers, and one or multiple emissivelayers between the cathode and anode. Since OLED is a self-emittingsolid state device, it offers tremendous potential for display andlighting applications. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on flexible substrates.

OLED can be categorized as three different types according to itsemitting mechanism. The OLED invented by Tang and van Slyke is afluorescent OLED. It only utilizes singlet emission. The tripletsgenerated in the device are wasted through nonradiative decay channels.Therefore, the internal quantum efficiency (IQE) of a fluorescent OLEDis only 25%. This limitation hindered the commercialization of OLED. In1997, Forrest and Thompson reported phosphorescent OLED, which usestriplet emission from heave metal containing complexes as the emitter.As a result, both singlet and triplets can be harvested, achieving 100%IQE. The discovery and development of phosphorescent OLED contributeddirectly to the commercialization of active-matrix OLED (AMOLED) due toits high efficiency. Recently, Adachi achieved high efficiency throughthermally activated delayed fluorescence (TADF) of organic compounds.These emitters have small singlet-triplet gap that makes the transitionfrom triplet back to singlet possible. In the TADF device, the tripletexcitons can go through reverse intersystem crossing to generate singletexcitons, resulting in high IQE.

OLEDs can also be classified as small molecule and polymer OLEDsaccording to the forms of the materials used. Small molecule refers toany organic or organometallic material that is not a polymer. Themolecular weight of a small molecule can be large as long as it has welldefined structure. Dendrimers with well-defined structures areconsidered as small molecules. Polymer OLEDs include conjugated polymersand non-conjugated polymers with pendant emitting groups. Small moleculeOLED can become a polymer OLED if post polymerization occurred duringthe fabrication process.

There are various methods for OLED fabrication. Small molecule OLEDs aregenerally fabricated by vacuum thermal evaporation. Polymer OLEDs arefabricated by solution process, such as spin-coating, ink-jet printing,and nozzle printing. Small molecule OLEDs can also be fabricated bysolution process if the materials can be dissolved or dispersed insolvents.

The emitting color of an OLED can be achieved by emitter structuraldesign. An OLED may comprise one emitting layer or a plurality ofemitting layers to achieve desired spectrum. In the case of green,yellow, and red OLEDs, phosphorescent emitters have successfully reachedcommercialization. Blue phosphorescent emitters still suffer fromnon-saturated blue color, short device lifetime, and high operatingvoltage. Commercial full-color OLED displays normally adopt a hybridstrategy, using fluorescent blue and phosphorescent yellow, or red andgreen. At present, efficiency roll-off of phosphorescent OLEDs at highbrightness remains a problem. In addition, it is desirable to have moresaturated emitting color, higher efficiency, and longer device lifetime.For fluorescent blue OLEDs, the color saturation, device efficiency, anddevice lifetime need to be improved to reduce power consumption. In themeantime, TADF devices haven't reached the lifetime goal forcommercialization. TADF emitters also need to improve their colorpurity, severe efficiency roll-off, and device lifetime.

Blue OLEDs suffer from short device lifetime and low efficiency. Thereis a great need to improve blue OLEDs lifetime and efficiency. Blueemitters with thermally activated delayed fluorescence (TADF) have beenapplied to achieve high EQE. However, most of the TADF emitters exhibitvery broad emission, making them undesirable for display applications.Furthermore, the lifetime of TADF devices is still not up to theindustry standard for display applications. TADF devices also havesevere efficiency roll-off at high brightness.

3. SUMMARY OF THE INVENTION

The present invention aims to provide a novel compound to solve theabove problems. The new compound exhibits narrow line shape and highphotoluminescence quantum yield.

According to an embodiment of the present invention, a compound having astructure according to the following Formula I is disclosed:

wherein Ring A, B, C, and D are each independently 5 or 6 membered arylor heteroaryl rings;

wherein R₁, R₂, R₃ and R₄ each independently represent no substitutionor up to the maximum available substitutions;

wherein R₁, R₂, R₃ and R₄ are each independently selected from the groupconsisting of hydrogen, deuterium, halogen, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, asubstituted or unsubstituted heteroalkyl group having 1 to 20 carbonatoms, a substituted or unsubstituted arylalkyl group having 7 to 30carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20carbon atoms, a substituted or unsubstituted aryloxy group having 6 to30 carbon atoms, a substituted or unsubstituted alkenyl group having 2to 20 carbon atoms, a substituted or unsubstituted aryl group having 6to 30 carbon atoms, a substituted or unsubstituted heteroaryl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted alkylsilylgroup having 3 to 20 carbon atoms, a substituted or unsubstitutedarylsilyl group having 6 to 20 carbon atoms, a substituted orunsubstituted amino group having 0 to 20 carbon atoms, an acyl group, acarbonyl group, a carboxylic acid group, an ester group, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof;

any adjacent substitutions can be optionally joined to form a ring;

wherein Y is NR, O, PR, S or Se;

wherein R is selected from the group consisting of hydrogen, deuterium,halogen, a substituted or unsubstituted alkyl group having 1 to 20carbon atoms, a substituted or unsubstituted cycloalkyl group having 3to 20 ring carbon atoms, a substituted or unsubstituted heteroalkylgroup having 1 to 20 carbon atoms, a substituted or unsubstitutedarylalkyl group having 7 to 30 carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted orunsubstituted aryloxy group having 6 to 30 carbon atoms, a substitutedor unsubstituted alkenyl group having 2 to 20 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 30 carbon atoms, asubstituted or unsubstituted heteroaryl group having 3 to 30 carbonatoms, a substituted or unsubstituted alkylsilyl group having 3 to 20carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to20 carbon atoms, a substituted or unsubstituted amino group having 0 to20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acidgroup, an ester group, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof;

wherein Z is N or P; and

wherein X₁ to X₁₀ are independently selected from the group consistingof B, C and N.

According to another embodiment, a first organic light-emitting deviceis disclosed. The first organic light-emitting device comprising: ananode; a cathode; and an organic layer, disposed between the anode andthe cathode, comprising a compound having a structure of Formula I:

wherein Ring A, B, C, and D are each independently 5 or 6 membered arylor heteroaryl rings;

wherein R₁, R₂, R₃ and R₄ each independently represent no substitutionor up to the maximum available substitutions;

wherein R₁, R₂, R₃ and R₄ are each independently selected from the groupconsisting of hydrogen, deuterium, halogen, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, asubstituted or unsubstituted heteroalkyl group having 1 to 20 carbonatoms, a substituted or unsubstituted arylalkyl group having 7 to 30carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20carbon atoms, a substituted or unsubstituted aryloxy group having 6 to30 carbon atoms, a substituted or unsubstituted alkenyl group having 2to 20 carbon atoms, a substituted or unsubstituted aryl group having 6to 30 carbon atoms, a substituted or unsubstituted heteroaryl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted alkylsilylgroup having 3 to 20 carbon atoms, a substituted or unsubstitutedarylsilyl group having 6 to 20 carbon atoms, a substituted orunsubstituted amino group having 0 to 20 carbon atoms, an acyl group, acarbonyl group, a carboxylic acid group, an ester group, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof;

any adjacent substitutions can be optionally joined to form a ring;

wherein Y is NR, O, PR, S or Se;

wherein R is selected from the group consisting of hydrogen, deuterium,halogen, a substituted or unsubstituted alkyl group having 1 to 20carbon atoms, a substituted or unsubstituted cycloalkyl group having 3to 20 ring carbon atoms, a substituted or unsubstituted heteroalkylgroup having 1 to 20 carbon atoms, a substituted or unsubstitutedarylalkyl group having 7 to 30 carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted orunsubstituted aryloxy group having 6 to 30 carbon atoms, a substitutedor unsubstituted alkenyl group having 2 to 20 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 30 carbon atoms, asubstituted or unsubstituted heteroaryl group having 3 to 30 carbonatoms, a substituted or unsubstituted alkylsilyl group having 3 to 20carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to20 carbon atoms, a substituted or unsubstituted amino group having 0 to20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acidgroup, an ester group, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof;

wherein Z is N or P; and

wherein X₁ to X₁₀ are independently selected from the group consistingof B, C and N.

According to yet another embodiment, a formulation comprising a compoundhaving a structure according to Formula I is also disclosed.

The novel boron containing heterocyclic compounds for OLEDs disclosed inthe present invention exhibit narrow line shape and highphotoluminescence quantum yield. The compounds can be used in OLEDs asemitters, hosts, charge blocking materials, charge transport materials,etc. The compounds can be easily used in the manufacture of OLEDs, whichcan provide efficient OLEDs and long lifetime.

4. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows an organic light emitting device that canincorporate the compound material disclosed herein.

FIG. 2 schematically shows another organic light emitting device thatcan incorporate the compound material disclosed herein.

FIG. 3 shows the compound of Formula I disclosed herein.

5. DETAILED DESCRIPTION

OLEDs can be fabricated on various types of substrates such as glass,plastic, and metal foil. FIG. 1 schematically shows the organic lightemitting device 100 without limitation. The figures are not necessarilydrawn to scale. Some of the layer in the figure can also be omitted asneeded. Device 100 may include a substrate 101, an anode 110, a holeinjection layer 120, a hole transport layer 130, an electron blockinglayer 140, an emissive layer 150, a hole blocking layer 160, an electrontransport layer 170, an electron injection layer 180 and a cathode 190.Device 100 may be fabricated by depositing the layers described inorder. The properties and functions of these various layers, as well asexample materials, are described in more detail in U.S. Pat. No.7,279,704 at cols. 6-10, which are incorporated by reference in itsentirety.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of host materials are disclosed inU.S. Pat. No. 6,303,238 to Thompson et al., which is incorporated byreference in its entirety. An example of an n-doped electron transportlayer is BPhen doped with Li at a molar ratio of 1:1, as disclosed inU.S. Patent Application Publication No. 2003/0230980, which isincorporated by reference in its entirety. U.S. Pat. Nos. 5,703,436 and5,707,745, which are incorporated by reference in their entireties,disclose examples of cathodes including compound cathodes having a thinlayer of metal such as Mg:Ag with an overlying transparent,electrically-conductive, sputter-deposited ITO layer. The theory and useof blocking layers is described in more detail in U.S. Pat. No.6,097,147 and U.S. Patent Application Publication No. 2003/0230980,which are incorporated by reference in their entireties. Examples ofinjection layers are provided in U.S. Patent Application Publication No.2004/0174116, which is incorporated by reference in its entirety. Adescription of protective layers may be found in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety.

The layered structure described above is provided by way of non-limitingexample. Functional OLEDs may be achieved by combining the variouslayers described in different ways, or layers may be omitted entirely.It may also include other layers not specifically described. Within eachlayer, a single material or a mixture of multiple materials can be usedto achieve optimum performance. Any functional layer may include severalsublayers. For example, the emissive layer may have a two layers ofdifferent emitting materials to achieve desired emission spectrum.

In one embodiment, an OLED may be described as having an “organic layer”disposed between a cathode and an anode. This organic layer may comprisea single layer or multiple layers.

An OLED can be encapsulated by a barrier layer to protect it fromharmful species from the environment such as moisture and oxygen. FIG. 2schematically shows the organic light emitting device 200 withoutlimitation. FIG. 2 differs from FIG. 1 in that the organic lightemitting device 200 include a barrier layer 102, which is above thecathode 190. Any material that can provide the barrier function can beused as the barrier layer such as glass and organic-inorganic hybridlayers. The barrier layer should be placed directly or indirectlyoutside of the OLED device. Multilayer thin film encapsulation wasdescribed in U.S. Pat. No. 7,968,146, which is herein incorporated byreference in its entirety.

Devices fabricated in accordance with embodiments of the invention canbe incorporated into a wide variety of consumer products that have oneor more of the electronic component modules (or units) incorporatedtherein. Some examples of such consumer products include flat paneldisplays, monitors, medical monitors, televisions, billboards, lightsfor interior or exterior illumination and/or signaling, heads-updisplays, fully or partially transparent displays, flexible displays,smart phones, tablets, phablets, wearable devices, smart watches, laptopcomputers, digital cameras, camcorders, viewfinders, micro-displays, 3-Ddisplays, vehicles displays, and vehicle tail lights.

The materials and structures described herein may be used in otherorganic electronic devices listed above.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

It is believed that the internal quantum efficiency (IQE) of fluorescentOLEDs can exceed the 25% spin statistics limit through delayedfluorescence. As used herein, there are two types of delayedfluorescence, i.e. P-type delayed fluorescence and E-type delayedfluorescence. P-type delayed fluorescence is generated fromtriplet-triplet annihilation (TTA).

On the other hand, E-type delayed fluorescence does not rely on thecollision of two triplets, but rather on the transition between thetriplet states and the singlet excited states. Compounds that arecapable of generating E-type delayed fluorescence are required to havevery small singlet-triplet gaps to convert between energy states.Thermal energy can activate the transition from the triplet state backto the singlet state. This type of delayed fluorescence is also known asthermally activated delayed fluorescence (TADF). A distinctive featureof TADF is that the delayed component increases as temperature rises. Ifthe reverse intersystem crossing rate is fast enough to minimize thenon-radiative decay from the triplet state, the fraction of backpopulated singlet excited states can potentially reach 75%. The totalsinglet fraction can be 100%, far exceeding 25% of the spin statisticslimit for electrically generated excitons.

E-type delayed fluorescence characteristics can be found in an exciplexsystem or in a single compound. Without being bound by theory, it isbelieved that E-type delayed fluorescence requires the luminescentmaterial to have a small singlet-triplet energy gap (ΔE_(S-T)). Organic,non-metal containing, donor-acceptor luminescent materials may be ableto achieve this. The emission in these materials is often characterizedas a donor-acceptor charge-transfer (CT) type emission. The spatialseparation of the HOMO and LUMO in these donor-acceptor type compoundsoften results in small ΔE_(S-T). These states may involve CT states.Often, donor-acceptor luminescent materials are constructed byconnecting an electron donor moiety such as amino- orcarbazole-derivatives and an electron acceptor moiety such asN-containing six-membered aromatic rings.

Definition of Terms of Substituents

halogen or halide—as used herein includes fluorine, chlorine, bromine,and iodine.

Alkyl—contemplates both straight and branched chain alkyl groups.Examples of the alkyl group include methyl group, ethyl group, propylgroup, isopropyl group, n-butyl group, s-butyl group, isobutyl group,t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octylgroup, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group,n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecylgroup, n-heptadecyl group, n-octadecyl group, neopentyl group,1-methylpentyl group, 2-methylpentyl group, 1-pentylhexyl group,1-butylpentyl group, 1-heptyloctyl group, 3-methylpentyl group.Additionally, the alkyl group may be optionally substituted. The carbonsin the alkyl chain can be replaced by other hetero atoms. Of the above,preferred are methyl group, ethyl group, propyl group, isopropyl group,n-butyl group, s-butyl group, isobutyl group, t-butyl group, n-pentylgroup, and neopentyl group.

Cycloalkyl—as used herein contemplates cyclic alkyl groups. Preferredcycloalkyl groups are those containing 4 to 10 ring carbon atoms andincludes cyclobutyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl,4,4-dimethylcylcohexyl, 1-adamantyl, 2-adamantyl, 1-norbornyl,2-norbornyl and the like. Additionally, the cycloalkyl group may beoptionally substituted. The carbons in the ring can be replaced by otherhetero atoms.

Alkenyl—as used herein contemplates both straight and branched chainalkene groups. Preferred alkenyl groups are those containing two tofifteen carbon atoms. Examples of the alkenyl group include vinyl group,allyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group,1,3-butandienyl group, 1-methylvinyl group, styryl group,2,2-diphenylvinyl group, 1,2-diphenylvinyl group, 1-methylallyl group,1,1-dimethylallyl group, 2-methylallyl group, 1-phenylallyl group,2-phenylallyl group, 3-phenylallyl group, 3,3-diphenylallyl group,1,2-dimethylallyl group, 1-phenyl1-butenyl group, and 3-phenyl-1-butenylgroup. Additionally, the alkenyl group may be optionally substituted.

Alkynyl—as used herein contemplates both straight and branched chainalkyne groups. Preferred alkynyl groups are those containing two tofifteen carbon atoms. Additionally, the alkynyl group may be optionallysubstituted.

Aryl or aromatic group—as used herein contemplates noncondensed andcondensed systems. Preferred aryl groups are those containing six tosixty carbon atoms, preferably six to twenty carbon atoms, morepreferably six to twelve carbon atoms. Examples of the aryl groupinclude phenyl, biphenyl, terphenyl, triphenylene, tetraphenylene,naphthalene, anthracene, phenalene, phenanthrene, fluorene, pyrene,chrysene, perylene, and azulene, preferably phenyl, biphenyl, terphenyl,triphenylene, fluorene, and naphthalene. Additionally, the aryl groupmay be optionally substituted. Examples of the non-condensed aryl groupinclude phenyl group, biphenyl-2-yl group, biphenyl-3-yl group,biphenyl-4-yl group, p-terphenyl-4-yl group, p-terphenyl-3-yl group,p-terphenyl-2-yl group, m-terphenyl-4-yl group, m-terphenyl-3-yl group,m-terphenyl-2-yl group, o-tolyl group, m-tolyl group, p-tolyl group,p-t-butylphenyl group, p-(2-phenylpropyl)phenyl group,4′-methylbiphenylyl group, 4″-t-butyl p-terphenyl-4-yl group, o-cumenylgroup, m-cumenyl group, p-cumenyl group, 2,3-xylyl group, 3,4-xylylgroup, 2,5-xylyl group, mesityl group, and m-quarterphenyl group.

Heterocyclic group or heterocycle—as used herein contemplates aromaticand non-aromatic cyclic groups. Hetero-aromatic also means heteroaryl.Preferred non-aromatic heterocyclic groups are those containing 3 to 7ring atoms which includes at least one hetero atom such as nitrogen,oxygen, and sulfur. The heterocyclic group can also be an aromaticheterocyclic group having at least one heteroatom selected from nitrogenatom, oxygen atom, sulfur atom, and selenium atom.

Heteroaryl—as used herein contemplates noncondensed and condensedhetero-aromatic groups that may include from one to five heteroatoms.Preferred heteroaryl groups are those containing three to thirty carbonatoms, preferably three to twenty carbon atoms, more preferably three totwelve carbon atoms. Suitable heteroaryl groups includedibenzothiophene, dibenzofuran, dibenzoselenophene, furan, thiophene,benzofuran, benzothiophene, benzoselenophene, carbazole,indolocarbazole, pyridylindole, pyrrolodipyridine, pyrazole, imidazole,triazole, oxazole, thiazole, oxadiazole, oxatriazole, dioxazole,thiadiazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine,oxazine, oxathiazine, oxadiazine, indole, benzimidazole, indazole,indoxazine, benzoxazole, benzisoxazole, benzothiazole, quinoline,isoquinoline, cinnoline, quinazoline, quinoxaline, naphthyridine,phthalazine, pteridine, xanthene, acridine, phenazine, phenothiazine,phenoxazine, benzofuropyridine, furodipyridine, benzothienopyridine,thienodipyridine, benzoselenophenopyridine, and selenophenodipyridine,preferably dibenzothiophene, dibenzofuran, dibenzoselenophene,carbazole, indolocarbazole, imidazole, pyridine, triazine,benzimidazole, 1,2-azaborine, 1,3-azaborine, 1,4-azaborine, borazine,and aza-analogs thereof. Additionally, the heteroaryl group may beoptionally substituted.

Alkoxy—it is represented by —O-Alkyl. Examples and preferred examplesthereof are the same as those described above. Examples of the alkoxygroup having 1 to 20 carbon atoms, preferably 1 to 6 carbon atomsinclude methoxy group, ethoxy group, propoxy group, butoxy group,pentyloxy group, and hexyloxy group. The alkoxy group having 3 or morecarbon atoms may be linear, cyclic or branched.

Aryloxy—it is represented by —O-Aryl or —O-heteroaryl. Examples andpreferred examples thereof are the same as those described above.Examples of the aryloxy group having 6 to 40 carbon atoms includephenoxy group and biphenyloxy group.

Arylalkyl—as used herein contemplates an alkyl group that has an arylsubstituent. Additionally, the arylalkyl group may be optionallysubstituted. Examples of the arylalkyl group include benzyl group,1-phenylethyl group, 2-phenylethyl group, 1-phenylisopropyl group,2-phenylisopropyl group, phenyl-t-butyl group, alpha.-naphthylmethylgroup, 1-alpha.-naphthylethyl group, 2-alpha-naphthylethyl group,1-alpha-naphthylisopropyl group, 2-alpha-naphthylisopropyl group,beta-naphthylmethyl group, 1-beta-naphthylethyl group,2-beta-naphthylethyl group, 1-beta-naphthylisopropyl group,2-beta-naphthylisopropyl group, p-methylbenzyl group, m-methylbenzylgroup, o-methylbenzyl group, p-chlorobenzyl group, m-chlorobenzyl group,o-chlorobenzyl group, p-bromobenzyl group, m-bromobenzyl group,o-bromobenzyl group, p-iodobenzyl group, m-iodobenzyl group,o-iodobenzyl group, p-hydroxybenzyl group, m-hydroxybenzyl group,o-hydroxybenzyl group, p-aminobenzyl group, m-aminobenzyl group,o-aminobenzyl group, p-nitrobenzyl group, m-nitrobenzyl group,o-nitrobenzyl group, p-cyanobenzyl group, m-cyanobenzyl group,o-cyanobenzyl group, 1-hydroxy-2-phenylisopropyl group, and1-chloro2-phenylisopropyl group. Of the above, preferred are benzylgroup, p-cyanobenzyl group, m-cyanobenzyl group, o-cyanobenzyl group,1-phenylethyl group, 2-phenylethyl group, 1-phenylisopropyl group, and2-phenylisopropyl group.

The term “aza” in azadibenzofuran, aza-dibenzothiophene, etc. means thatone or more of the C—H groups in the respective aromatic fragment arereplaced by a nitrogen atom. For example, azatriphenylene encompassesdibenzo[f,h]quinoxaline,dibenzo[f,h]quinoline and other analogues withtwo or more nitrogens in the ring system. One of ordinary skill in theart can readily envision other nitrogen analogs of the aza-derivativesdescribed above, and all such analogs are intended to be encompassed bythe terms as set forth herein.

The alkyl, cycloalkyl, alkenyl, alkynyl, aralkyl, heterocyclic group,aryl, and heteroaryl may be unsubstituted or may be substituted with oneor more substituents selected from the group consisting of deuterium,halogen, alkyl, cycloalkyl, arylalkyl, alkoxy, aryloxy, amino, cyclicamino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl,heteroaryl, acyl, carbonyl, carboxylic acid, ether, ester, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof.

It is to be understood that when a molecular fragment is described asbeing a substituent or otherwise attached to another moiety, its namemay be written as if it were a fragment (e.g. phenyl, phenylene,naphthyl, dibenzofuryl) or as if it were the whole molecule (e.g.benzene, naphthalene, dibenzofuran). As used herein, these differentways of designating a substituent or attached fragment are considered tobe equivalent.

In the compounds mentioned in this disclosure, the hydrogen atoms can bepartially or fully replaced by deuterium. Other atoms such as carbon andnitrogen, can also be replaced by their other stable isotopes. Thereplacement by other stable isotopes in the compounds may be preferreddue to its enhancements of device efficiency and stability.

The novel boron containing heterocyclic compounds disclosed in thepresent invention exhibit narrow line shape and high photoluminescencequantum yield. The compounds can be used in OLEDs as emitters, hosts,charge blocking materials, charge transport materials, etc.

According to an embodiment of the present, a compound having a structureaccording to the following Formula I is disclosed:

wherein Ring A, B, C, and D are each independently 5 or 6 membered arylor heteroaryl rings;

wherein R₁, R₂, R₃ and R₄ each independently represent no substitutionor up to the maximum available substitutions;

wherein R₁, R₂, R₃ and R₄ are each independently selected from the groupconsisting of hydrogen, deuterium, halogen, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted cycloalkyl group having 3 to 20 ring carbon atoms—asubstituted or unsubstituted heteroalkyl group having 1 to 20 carbonatoms, a substituted or unsubstituted arylalkyl group having 7 to 30carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20carbon atoms, a substituted or unsubstituted aryloxy group having 6 to30 carbon atoms, a substituted or unsubstituted alkenyl group having 2to 20 carbon atoms, a substituted or unsubstituted aryl group having 6to 30 carbon atoms, a substituted or unsubstituted heteroaryl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted alkylsilylgroup having 3 to 20 carbon atoms, a substituted or unsubstitutedarylsilyl group having 6 to 20 carbon atoms, a substituted orunsubstituted amino group having 0 to 20 carbon atoms, an acyl group, acarbonyl group, a carboxylic acid group, an ester group, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof;

any adjacent substitutions can be optionally joined to form a ring;

Wherein Y is NR group, PR group, element O, element S or element Se;wherein said R is selected from the group consisting of hydrogen,deuterium, halogen, a substituted or unsubstituted alkyl group having 1to 20 carbon atoms, a substituted or unsubstituted cycloalkyl grouphaving 3 to 20 ring carbon atoms, a substituted or unsubstitutedheteroalkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted arylalkyl group having 7 to 30 carbon atoms, a substitutedor unsubstituted alkoxy group having 1 to 20 carbon atoms, a substitutedor unsubstituted aryloxy group having 6 to 30 carbon atoms, asubstituted or unsubstituted alkenyl group having 2 to 20 carbon atoms,a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, asubstituted or unsubstituted heteroaryl group having 3 to 30 carbonatoms, a substituted or unsubstituted alkylsilyl group having 3 to 20carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to20 carbon atoms, a substituted or unsubstituted amino group having 0 to20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acidgroup, an ester group, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof;

wherein Z is N or P; and

wherein X₁ to X₁₀ are independently selected from the group consistingof B, C and N.

In one embodiment, wherein ring A, B, C, and D are each independently 6membered aryl or heteroaryl rings.

In one embodiment, wherein X₁ to X₁₀ are C.

In one embodiment, wherein Z is N.

In one embodiment, wherein Y is NR.

In one embodiment, wherein Z is N and Y is NR.

In one embodiment, wherein R of formula I is aryl or heteroaryl.

In one preferred embodiment, wherein the compound of formula I isselected from the group consisting of:

In one preferred embodiment, wherein the compound of formula I isselected from the group consisting of:

In one preferred embodiment, wherein the compound of formula I isselected from the group consisting of:

In one embodiment, wherein Y is O.

In one preferred embodiment, wherein the compound of formula I isselected from the group consisting of:

In one embodiment, wherein at least one of ring A, B, C, and D is a 5membered heteroaryl ring.

In one preferred embodiment, wherein the compound of formula I isselected from the group consisting of:

In one embodiment, wherein at least one R, R₁, R₂, R₃ or R₄ comprises asubstituent selected from the group consisting of phenyl, biphenyl,poly-phenyl, diarylamine, carbazole, azacarbazole, dibenzofuran,azadibenzofuran, dibenzothiophene, azadibenzothiophene,dibenzoselenophene, azadibenzoselenophene, triphenylene,azatriphenylene, tetraphenylene, diarylsilyl, triarylsilyl.

In one embodiment, wherein at least one R, R₁, R₂, R₃ or R₄ comprises asubstituent selected from the group consisting of phenyl, biphenyl,poly-phenyl, diarylamine, carbazole, azacarbazole, dibenzofuran,azadibenzofuran, dibenzothiophene, azadibenzothiophene,dibenzoselenophene, azadibenzoselenophene, triphenylene,azatriphenylene, tetraphenylene, diarylsilyl, triarylsilyl; and theremaining of R, R₁, R₂, R₃ or R₄ are H.

According to another embodiment, a first organic light-emitting deviceis disclosed. The first organic light-emitting device comprising: ananode; a cathode; and an organic layer, disposed between the anode andthe cathode, comprising a compound having a structure of Formula I:

wherein Ring A, B, C, and D are each independently 5 or 6 membered arylor heteroaryl rings;

wherein R₁, R₂, R₃ and R₄ each independently represent no substitutionor up to the maximum available substitutions;

wherein R₁, R₂, R₃ and R₄ are each independently selected from the groupconsisting of hydrogen, deuterium, halogen, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, asubstituted or unsubstituted heteroalkyl group having 1 to 20 carbonatoms, a substituted or unsubstituted arylalkyl group having 7 to 30carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20carbon atoms, a substituted or unsubstituted aryloxy group having 6 to30 carbon atoms, a substituted or unsubstituted alkenyl group having 2to 20 carbon atoms, a substituted or unsubstituted aryl group having 6to 30 carbon atoms, a substituted or unsubstituted heteroaryl grouphaving 3 to 30 carbon atoms, a substituted or unsubstituted alkylsilylgroup having 3 to 20 carbon atoms, a substituted or unsubstitutedarylsilyl group having 6 to 20 carbon atoms, a substituted orunsubstituted amino group having 0 to 20 carbon atoms, an acyl group, acarbonyl group, a carboxylic acid group, an ester group, nitrile,isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinationsthereof;

any adjacent substitutions can be optionally joined to form a ring;

wherein Y is NR, O, PR, S or Se;

wherein R is selected from the group consisting of hydrogen, deuterium,halogen, a substituted or unsubstituted alkyl group having 1 to 20carbon atoms, a substituted or unsubstituted cycloalkyl group having 3to 20 ring carbon atoms, a substituted or unsubstituted heteroalkylgroup having 1 to 20 carbon atoms, a substituted or unsubstitutedarylalkyl group having 7 to 30 carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted orunsubstituted aryloxy group having 6 to 30 carbon atoms, a substitutedor unsubstituted alkenyl group having 2 to 20 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 30 carbon atoms, asubstituted or unsubstituted heteroaryl group having 3 to 30 carbonatoms, a substituted or unsubstituted alkylsilyl group having 3 to 20carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to20 carbon atoms, a substituted or unsubstituted amino group having 0 to20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acidgroup, an ester group, nitrile, isonitrile, sulfanyl, sulfinyl,sulfonyl, phosphino, and combinations thereof;

wherein Z is N or P; and

wherein X₁ to X₁₀ are independently selected from the group consistingof B, C and N.

In one embodiment, wherein the organic layer is an emissive layer andthe compound is an emitter.

In one embodiment, wherein the organic layer further comprises a host.

In one embodiment, wherein the organic layer is an emissive layer andthe compound is a host.

In one embodiment, wherein the organic layer is a charge carrierblocking layer and the compound is a charge carrier blocking material inthe organic layer.

In one embodiment, wherein the organic layer is a charge carriertransporting layer and the compound is a charge carrier transportingmaterial in the organic layer.

In one embodiment, wherein the first device is incorporated into adevice selected from the group consisting of a consumer product, anelectronic component module, an organic light-emitting device, and alighting panel.

According to yet another embodiment, a formulation comprising a compoundhaving a structure according to Formula I is also disclosed. Compoundsof formula I are described above.

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. The combinations ofthese materials are described in more detail in U.S. Pat. App. No.20160359122 at paragraphs 0133-0160, which are incorporated by referencein its entirety. The materials described or referred to the disclosureare non-limiting examples of materials that may be useful in combinationwith the compounds disclosed herein, and one of skill in the art canreadily consult the literature to identify other materials that may beuseful in combination.

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a varietyof other materials present in the device. For example, emissive dopantsdisclosed herein may be used in combination with a wide variety ofhosts, transport layers, blocking layers, injection layers, electrodesand other layers that may be present. The combination of these materialsis described in detail in paragraphs 0080-0101 of U.S. Pat. App. No.20150349273, which are incorporated by reference in its entirety. Thematerials described or referred to the disclosure are non-limitingexamples of materials that may be useful in combination with thecompounds disclosed herein, and one of skill in the art can readilyconsult the literature to identify other materials that may be useful incombination.

In the embodiments of material synthesis, all reactions were performedunder nitrogen protection unless otherwise stated. All reaction solventswere anhydrous and used as received from commercial sources. Syntheticproducts were structurally confirmed and tested for properties using oneor more conventional equipment in the art (including, but not limitedto, nuclear magnetic resonance instrument produced by BRUKER, liquidchromatograph produced by SHIMADZU, liquid chromatography-massspectrometer produced by SHIMADZU, gas chromatography-mass spectrometerproduced by SHIMADZU, differential Scanning calorimeters produced bySHIMADZU, fluorescence spectrophotometer produced by SHANGHAI LENGGUANGTECH., electrochemical workstation produced by WUHAN CORRTEST, andsublimation apparatus produced by ANHUI BEQ, etc.) by methods well knownto the persons skilled in the art. As the persons skilled in the art areaware of the above-mentioned equipment use, test methods and otherrelated contents, the inherent data of the sample can be obtained withcertainty and without influence, so the above related contents are notfurther described in this patent.

Example

The method for preparing the compounds of the present invention is notlimited. The compound 1 is exemplified as a typical but non-limitingexample, and its synthesis route and preparation method are as follows:

Synthesis of Compound 1

Step 1:

A mixture of 1,3-Diiodobenzene (100 g, 304 mmol), 2-Nitrophenylboronicacid (61 g, 365 mmol,), Pd(PPh₃)₄ (10.5 g, 9 mmol) and Na₂CO₃ (39 g, 365mmol) in 400 mL of toluene, 160 mL of EtOH and 160 mL of H₂O was bubbledwith N₂ for 10 min and refluxed under N₂ overnight. After evaporatingthe solvent, water was added. The mixture was extracted with ethylacetate for three times. The extracts were dried over MgSO₄, filtered,concentrated and column chromatographed (silica gel, gradient elutionfrom pure petroleum ether (PE) to 10:1 PE/CH₂Cl₂) to give3′-iodo-2-nitro-1,1′-biphenyl (35 g, 35% yield) as a light yellow solid.

Step 2:

A mixture of 1,3-Diiodobenzene (100 g, 304 mmol), aniline (28.3 g, 304mmol), t-BuONa (58 g, 610 mmol), Pd₂(dba)₃, (5.6 g, 6 mmol) and DPPF(6.6 g, 12 mmol) in 800 mL of anhydrous xylenes was bubbled with N₂ for10 min and refluxed under N₂ overnight. After evaporating the solvent,water was added. The mixture was extracted with ethyl acetate for threetimes. The extracts were dried over MgSO₄, filtered, concentrated andcolumn chromatographed (silica gel, gradient elution from pure PE to10:1 PE/CH₂Cl₂) to give 3-iodo-N-phenylaniline (35 g, 40% yield) as acolorless oil.

Step 3:

A mixture of 3-iodo-N-phenylaniline (35 g, 119 mmol),(2-bromophenyl)boronic acid (31 g, 155 mmol), Pd(PPh₃)₄ (6.9 g, 6 mmol)and Na₂CO₃ (25.4 g, 240 mmol) in 500 mL of dioxane and 100 mL of H₂O wasbubbled with N₂ for 10 min and refluxed under N₂ overnight. Afterevaporating the solvent, water was added. The mixture was extracted withethyl acetate for three times. The extracts were dried over MgSO₄,filtered, concentrated and column chromatographed (silica gel, gradientelution from 100:1 to 5:1 PE/CH₂Cl₂) to give2′-bromo-N-phenyl-[1,1′-biphenyl]-3-amine (27 g, 70% yield) as acolorless oil.

Step 4:

A mixture of 2′-bromo-N-phenyl-[1,1′-biphenyl]-3-amine (20 g, 62 mmol),3′-iodo-2-nitrobiphenyl (24 g, 74 mmol), Pd(OAc)₂ (560 mg, 2.5 mmol) andt-BuONa (12 g, 124 mmol) was purged with N₂ for 5 min. 200 mL ofanhydrous xylenes was added and the mixture was bubbled with N₂ for 5min. t-Bu₃P (5 mmol) in toluene (10% wt solution) was added and themixture was bubbled with N₂ for another 5 min. Then the reaction mixturewas then heated to 50° C. overnight. After evaporating the solvent,water was added. The mixture was extracted with ethyl acetate for threetimes. The extracts were dried over MgSO₄, filtered, concentrated andcolumn chromatographed (silica gel, gradient elution from 100:1 to 5:1PE/CH₂Cl₂) to give2′-bromo-N-(2′-nitro-[1,1′-biphenyl]-3-yl)-N-phenyl-[1,1′-biphenyl]-3-amine(20 g, 62% yield) as a white solid.

Step 5:

A mixture of2′-bromo-N-(2′-nitro-[1,1′-biphenyl]-3-yl)-N-phenyl-[1,1′-biphenyl]-3-amine(20 g, 38.5 mmol), and Na₂S₂O₄ (135 g, 770 mmol) in EtOH (200 mL), H₂O(200 mL) and toluene (100 ml) was bubbled with N₂ for 10 min andrefluxed until the reaction was completed. After evaporating thesolvent, water was added. The mixture was extracted with ethyl acetatefor three times. The extracts were dried over MgSO₄, filtered,concentrated and column chromatographed (silica gel, gradient elutionfrom 20:1 to 1:1 PE/CH₂Cl₂) to give the2′-bromo-N-(2′-amino-[1,1′-biphenyl]-3-yl)-N-phenyl-[1,1′-biphenyl]-3-amine(15 g, 80% yield) as a light yellow oil.

Step 6:

2′-bromo-N-(2′-amino-[1,1′-biphenyl]-3-yl)-N-phenyl-[1,1′-biphenyl]-3-amine(3 g, 6 mmol) in 50 mL of anhydrous xylenes was bubbled with N₂ for 10min and added to a 50 ml syringe. Separately, a mixture of Pd(OAc)₂ (270mg, 1.2 mmol,), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (1 g,2.4 mmol,) and t-BuONa (1.2 g, 12 mmol) in 550 mL of anhydrous xyleneswas bubbled with N₂ for 10 min and heated to 140° C. The2′-bromo-N-(2′-amino-[1,1′-biphenyl]-3-yl)-N-phenyl-[1,1′-biphenyl]-3-aminesolution was added to the heated solution via a syringe pump over 17.5h. After evaporating the solvent, water was added. The mixture wasextracted with ethyl acetate for three times. The extracts were driedover MgSO₄, filtered, concentrated and column chromatographed (silicagel, gradient elution from 50:1 to 5:1 PE/CH₂Cl₂) to give the cyclicamine (1.4 g, 57% yield) as a white solid.

Step 7:

The cyclic amine (2.5 g, 6.1 mmol) was dissolved in 150 mL o-DCB andcooled to 0° C. Then n-BuLi (6.7 mmol) was added dropwise. After 2 h,BBr₃ (3 eq) was added and stirred for another 8 h during which thetemperature was raised to room temperature. The reaction mixture wasthen heated to 190° C. overnight. After evaporating the solvent, waterwas added. The mixture was extracted with ethyl acetate for three times.The extracts were dried over MgSO₄, filtered, concentrated and columnchromatographed (silica gel, gradient elution from 100:1 to 10:1PE/CH₂Cl₂) to give Compound 1 (1.3 g, 50% yield) as a light green solid.The solid was further purified using reversed phase columnchromatography with ACN as the eluent to give a white solid, which wasidentified by NMR and MS as the desired product. ¹H NMR (400 MHz,CD₂Cl₂) δ 8.49 (dd, J₁=8.4 Hz, J₂=1.2 Hz, 2H), 8.46 (dd, J₁=8.0 Hz,J₂=1.6 Hz, 2H), 7.91 (d, J=7.6 Hz, 2H), 7.75-7.71 (m, 2H), 7.65-7.57 (m,3H), 7.50-7.46 (m, 2H), 7.43-7.41 (m, 2H), 7.40-7.34 (m, 2H), 6.52 (d,J=8.4 Hz, 2H). ¹³C NMR (100 MHz, CD₂Cl₂) δ 147.64, 141.35, 138.26,137.84, 132.12, 131.18, 130.47, 128.72, 127.93, 126.80, 126.14, 122.68,120.52, 119.13, 112.27, 112.26. HRMS (ESI, m/z): calcd for C₃₀H₁₉BN₂,[M+1]⁺: 419.1719; found: 419.1724]. Compound 1 showed strong deep blueemission in methylbenzene with an emission maximum at 430 nm and a FWHMof 34 nm. It shows that the design of the compounds of Formula I, due toits rigid cyclic structure, can exhibit narrow emissions.

The persons skilled in the art should know that the above preparationmethod is only an illustrative example, and the persons skilled in theart can obtain the structure of other compounds of the present inventionby modifying the above preparation method.

It is understood that the various embodiments described herein are byway of example only and are not intended to limit the scope of theinvention. The present invention as claimed may therefore includevariations from the particular examples and preferred embodimentsdescribed herein, as will be apparent to one of skill in the art. Manyof the materials and structures described herein may be substituted withother materials and structures without deviating from the spirit of theinvention. It is understood that various theories as to why theinvention works are not intended to be limiting.

What is claimed is:
 1. A compound having Formula I:

wherein Ring A, B, C, and D are each independently 5 or 6 membered aryl or heteroaryl rings; wherein R₁, R₂, R₃ and R₄ each independently represent no substitution or up to the maximum available substitutions; wherein R₁, R₂, R₃ and R₄ are each independently selected from the group consisting of hydrogen, deuterium, halogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted alkylsilyl group having 3 to 20 carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; any adjacent substitutions can be optionally joined to form a ring; wherein Y is NR, O, PR, S or Se; wherein R is selected from the group consisting of hydrogen, deuterium, halogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted alkylsilyl group having 3 to 20 carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein Z is N or P; and wherein X₁ to X₁₀ are independently selected from the group consisting of C and N, and wherein at most one of X₁ to X₁₀ is N.
 2. The compound of claim 1, wherein ring A, B, C, and D are each independently 6 membered aryl or heteroaryl rings.
 3. The compound of claim 1, wherein each of X₁ to X₁₀ is C.
 4. The compound of claim 1, wherein Z is N.
 5. The compound of claim 1, wherein Y is NR.
 6. The compound of claim 1, wherein Z is N and Y is NR.
 7. The compound of claim 6, wherein R is aryl or heteroaryl.
 8. The compound of claim 1, wherein the compound is selected from the group consisting of:


9. The compound of claim 1, wherein Y is O.
 10. The compound of claim 9, wherein the compound is selected from the group consisting of:


11. The compound of claim 1, wherein at least one of ring A, B, C, and D is a 5 membered heteroaryl ring.
 12. The compound of claim 11, wherein the compound is selected from the group consisting of:


13. The compound of claim 1, wherein at least one R, R₁, R₂, R₃ or R₄ comprises a substituent selected from the group consisting of phenyl, biphenyl, poly-phenyl, diarylamine, carbazole, azacarbazole, dibenzofuran, azadibenzofuran, dibenzothiophene, azadibenzothiophene, dibenzoselenophene, azadibenzoselenophene, triphenylene, azatriphenylene, tetraphenylene, diarylsilyl, triarylsilyl.
 14. A first organic light-emitting device comprising: an anode; a cathode; and an organic layer, disposed between the anode and the cathode, comprising a compound having a structure of Formula I:

wherein Ring A, B, C, and D are each independently 5 or 6 membered aryl or heteroaryl rings; wherein R₁, R₂, R₃ and R₄ each independently represent no substitution or up to the maximum available substitutions; wherein R₁, R₂, R₃ and R₄ are each independently selected from the group consisting of hydrogen, deuterium, halogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted alkylsilyl group having 3 to 20 carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; any adjacent substitutions can be optionally joined to form a ring; wherein Y is NR, O, PR, S or Se; wherein R is selected from the group consisting of hydrogen, deuterium, halogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted alkylsilyl group having 3 to 20 carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to 20 carbon atoms, a substituted or unsubstituted amino group having 0 to 20 carbon atoms, an acyl group, a carbonyl group, a carboxylic acid group, an ester group, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, phosphino, and combinations thereof; wherein Z is N or P; and wherein X₁ to X₁₀ are independently selected from the group consisting of C and N, and wherein at most one of X₁ to X₁₀ is N.
 15. The first device of claim 14, wherein the organic layer is an emissive layer and the compound is an emitter.
 16. The first device of claim 15, wherein the organic layer further comprises a host.
 17. The first device of claim 14, wherein the organic layer is an emissive layer and the compound is a host.
 18. The first device of claim 14, wherein the organic layer is a charge carrier blocking layer and the compound is a charge carrier blocking material in the organic layer.
 19. The first device of claim 14, wherein the organic layer is a charge carrier transporting layer and the compound is a charge carrier transporting material in the organic layer.
 20. The first device of claim 14, wherein the first device is incorporated into a device selected from the group consisting of a consumer product, an electronic component module, an organic light-emitting device, and a lighting panel.
 21. A formulation comprising a compound according to claim
 1. 22. The compound of claim 1, wherein X₁ is N or C, and each of X₂ to X₁₀ is C.
 23. The first device of claim 14, wherein X₁ is N or C, and each of X₂ to X₁₀ is C.
 24. The first device of claim 14, wherein each of X₁ to X₁₀ is C. 